The present invention relates to a positioning arrangement and more particularly, to a positioning arrangement for a boom or jib structure which supports, for example, a drilling machine such as a machine drill, i.e., rock drill, rock borer or the like.
Commonly drilling machines, for example, rock drills or rock borers are widely employed in mining, tunnel excavation, etc., for drilling rocks to form openings or holes in such rocks so as to enable placing therein of explosives and the like for blasting or for sampling rock cuttings to determine the mineral content of ore. Such a drilling machine is normally supported by an associated boom or jib structure which is mounted on a vehicle such as a truck or crawler so as to be operated, for example, by hydraulic rams for correct positioning of a bit of the drilling machine with respect to the rock or object to be drilled.
The conventional arrangement as described above, however, has a serious disadvantage in that, since the movement of the boom structure is based on particular spherical coordinates or spherical loci different from rectangular coordinates or rectangular loci well suited to human senses, it has been extremely difficult to designate proper positions of such a boom structure in an efficient manner. More specifically, in the conventional arrangement as described above, it is a general practice, for example, as disclosed in U.S. Pat. No. 3,980,142, to set up a servo or servo-mechanism by detecting displacement of the hydraulic cylinders for driving the boom structure, and since it is difficult to numerically designate the position of the boom end, i.e., the position of the bit of the drilling machine, there has been employed a system known as a reproduction control system (i.e., utilizing the so-called play back method) in which the positioning work is preliminarily effected by manual operation so as to be memorized for subsequent reproduction. The known play back method as described above, however, has drawbacks as follows.
(i) The designated values tend to be erroneous. PA1 (ii) The programming depends solely on human skill. PA1 (iii) Numerical designation can not be effected. PA1 (iv) Since the programming is effected by the working maching, (i.e. drilling machine) itself, such working machine can not be operated during the programming, with consequent reduction in working efficiency. PA1 (v) In a drilling machine having a complicated boom construction, for example, for smooth brushing boring, etc., considerable time is required for the programming work.